This invention relates to pop-up irrigation sprinklers of the type contained within a casing buried in the ground, and more particularly to a new and improved pop-up guard or shield for preventing dirt, grit, weeds, sand, grass and the like from entering the housing during operation of the sprinkler.
There are many applications for pop-up sprinklers wherein the sprinkler is contained within a casing buried in the ground and which pops up to a position above the casing during operation. Typically, the sprinkler casing is buried in the ground so that its top surface is substantially flush with the ground level, and the sprinkler is spring-biased to the inoperative position retracted inside the casing. A cover is typically attached to the sprinkler and overlies the top of the casing when the sprinkler is in the inoperative position. During irrigation, water is supplied to the sprinkler through the bottom of the casing and the sprinkler extends to the operative position by popping up out of the casing to a position above the ground, the sprinkler carrying the cover with it during its movement to the extended, operative position. Exemplary of sprinklers of this type are those marketed by Rain Bird Sprinkler Mfg. Corp. of Glendora, Calif., under its trademarks "Mini Paw" and "Pop-A-Way" as shown at pages 32 and 33 of the Rain Bird 1986 Turf Irrigation Equipment Catalogue.
Pop-up sprinklers of the general type herein involved are widely used in connection with lawns, golf courses, parks, and other installations where it is undesirable to have a permanently-mounted sprinkler projecting above the ground when not in use. One problem that has long been encountered in the use of such pop-up sprinklers is that of dirt, sand, weeds, grass, and other deleterious particulate matter entering the open top of the sprinkler casing during sprinkler operation and which can cause the sprinkler to jam such that it either does not pop up all the way to the operative position, or does not fully retract into the casing after use. This problem has been particularly noticeable where pop-up sprinklers are used in sandy and gravel-concentrated soils.
While attempts have heretofore been made at solving this problem, none has proved completely satisfactory. Exemplary of such prior art attempts are the use of static shields and guards which are placed around the sprinkler casing to form a plate-like area or well surrounding the sprinkler such as shown and described in U.S. Pat. Nos. 3,762,642 and 4,108,439. Although such prior art devices have met with some success, they still do not prevent deleterious particulate matter on the ground from falling or being backwashed into the open-topped casing during sprinkler operation, particularly during extension and retraction of the sprinkler relative to the casing.
Thus, there exists a need for a reliable and effective shield or guard to prevent deleterious particulate matter from entering the sprinkler casing during sprinkler operation. The present invention satisfies this need.